AMD's 790GX: I'm Down with ACC

690G Til Now

About a year and a half ago AMD released one of the first usable integrated 3D graphics units, and it really was an astounding part for the time. The AMD 690G broke new ground in compatibility, usability, and feature sets for an integrated part. Many of the current games of the time could successfully be played on this integrated chipset, though at low quality levels at low resolutions; but it was a far cry from previous products from all other graphics camps (especially Intel).

The 690G provided AMD with a competitive platform which allowed them to win some designs from manufacturers, even though the Athlon X2 chips were lagging significantly behind Intel’s Core 2 series of products. Also consider the far more robust drivers that AMD was able to provide to these vendors vs. what Intel was able to offer. While the 690G did not steamroll AMD into profitability, it did allow the company to sell more chipsets and the accompanying CPUs to consumers and manufacturers.

What the 790GX means to you. Not a whole lot of difference overall from the 780G/SB 700 combo, but the addition of ACC is the secret sauce that makes the platform tick.

The 690G is based on the X700 chip, but with half of that particular product missing. It features 4 RBE/Tex units attached to 4 SM 2.0 units and a single vertex unit. This gives the 690G a decent amount of rendering grunt, and allows it to utilize Vista’s Aero. It also features the Avivo engine, though only in the SD format. It can handle higher definition content, but only with a dual core processor at 2.4 GHz and higher. Even with this combination, quality could take a nosedive in terms of incorrect color representation and/or dropped frames.

A few months back AMD released the 780G, which is a huge upgrade from the older 690G. The 780G is based on the RV610 graphics core, which powers the Radeon 3450 series of cards. It features quad RBEs (render back ends), quad texturing units, and 40 stream processors organized in two SIMD groups of 4 x 5 SPs. The 780G is clocked at a respectable 500 MHz, but it still relies on the CPU and main memory to handle all of its data needs. The 780G also supports Avivo HD and UVD, and if a motherboard manufacturer chooses to do so, the chip supports sideband memory (a decent amount of high speed memory attached directly to the IGP via a 16 bit pathway).

The chipset also includes two other major features; that being PCI-E 2.0 support over all lanes and the new SB700 southbridge which supposedly has fixed some of the performance issues previous AMD southbridges have experienced. PCI-E 2.0 support looks to be a painless transition, as compared to the AGP days of yore. The SB700 southie adds another pair of SATA ports, as well as two more USB 2.0 ports as well.

The 790GX is not aimed entirely at enthusiasts, as we can see from the official AMD documentation. The 790GX does bring a lot to the table for other interested parties, but we have to question if the faster integrated graphics is a big enough jump over the 780G to lure customers away.

The 780G has received a lot of attention, and rightly so. It is one of the fastest integrated choices out there. Users do not have to give up a lot of quality to play many of their favorite games, and the compatibility afforded by AMD’s Catalyst driver program insures that even the latest games will at least run correctly on the 780G. The 780G also introduced the concept of “Hybrid CrossFireX” which allows the IGP to be CrossFired with a discrete graphics card, namely the Radeon 3450. This will double the performance of the 780G platform in 3D graphics, all for an extra $50 or so which the discrete card costs.

If there is a downside to the 780G it is that the motherboard manufacturers decided to relegate it to the lower end of the price spectrum. Most of the motherboard designs based around this chip have basic power delivery systems, usually comprised of 3 phase arrays which can support a maximum of 95 watts (and less in certain products). Some manufacturers have released products which support up to 140 watt products, but these are few and far between. So the 780G is relegated to run mostly 65 nm Athlon X2 products, the triple core Phenoms, and a few of the lower power quad core Phenoms.

Now AMD has unleashed a new product on us, and one that is taking a different direction than other enthusiast products.